[T2] Disc brakes dragging

david raistrick keen at icantclick.org
Sun Aug 16 18:41:39 PDT 2020


I'd start with a fresh bed-in and get them hot.  that might sort out the
balance.  or scuff the pad surfaces and the rotors, then re-bed.

On Sun, Aug 16, 2020 at 9:14 PM Chris Dreike <cdreike at gmail.com> wrote:

> Thanks to you guys I installed 1/16" thick shims between the booster and
> the M/C. Problem is gone! I'll try some thinner shims until the problem
> returns and go with something thinner than 1/16. As it is now the pedal
> goes WAAAY down to about 1.5" above the floor. I'll lengthen the pedal to
> booster rod back to spec too.
>
> Now on to the next problem, the brakes pull to the left. I know that the
> driver disc got pretty hot one time before I realized the brake drag
> problem. The passenger side didn't get quite as hot. How can I remedy this?
> Have the disc turned? New pads?
>
> Success, of sorts, at last.
>
> thanks again.
> Chris
>
>
> On Sun, Aug 16, 2020 at 1:33 PM Chris Dreike <cdreike at gmail.com> wrote:
>
> > Wow, Thanks for all the input. All the parts are new save the steel brake
> > lines. The brakes worked fine before I installed the drop spindles.
> > I looked up How works a brake booster. The brake fluid level is not
> > dropping. There appears to be a weep hole at the bottom of the M/C
> mounting
> > flange. No fluid dripping out.
> > Yes the brakes are working fine with the vacuum line disconnected from
> the
> > intake manifold. The vacuum check valve is new and working as I checked
> the
> > function.
> > The vent line is in good working order. Sadly the boot at the front of
> the
> > booster is shot after an year and a half. Anyone know where to get a new
> > one? I'll try Wolfsburg West tomorrow.
> >
> > Later today I will add a small shim between the M/C and the booster and
> > see if that helps. The booster seems to be the problem. Will report back
> > later.
> >
> > Erik, Where is the check valve you mentioned earlier? Is it in the M/C?
> or
> > were you referring to the vacuum check valve in line to the manifold?
> >
> > AND one more thing. In perusing the forums on the Samba I found a post
> > complaining of exactly the problem I'm having. New booster from Wolfburg
> (
> > I got mine from CIP1 and it looks to be the same manufacturer) and his
> disc
> > brakes were dragging. I did not see a solution on that thread however
> there
> > were a lot of posts saying to have your old OEM booster rebuilt rather
> than
> > buy a new one as the new ones are problematic.
> >
> > Cheers,
> > Chris
> >
> > On Sun, Aug 16, 2020 at 7:10 AM Jamie <jrivers at globalserve.net> wrote:
> >
> >> Inside the booster, there is a valve, opens on brake application and
> >> allows vac to assist movement Of cylinder in master cylinder
> >>
> >> If fluid is in that area, it will hold the port open,, and keep brakes
> >> applied while vacuum is available
> >>
> >> and when more fluid gets in there ,,A slight tap of the pedal will cause
> >> the vac to depress it and pull it out from under your foot, and apply
> >> brakes fairly hard!
> >>
> >> Sounds to me that there is fluid that has bypassed seal on master ,,,
> >> over the years,, so you don’t notice a recent drop in fluid in the
> >> reservoir,,
> >>
> >> Pull the master (loosen off far enough) and field fab a dip stick from
> >> box board to slide into booster below the master .. see if there is
> fluid
> >> in there
> >> I don’t worry about a little fluid,,
> >>
> >> If there is a “lot” <relatively speaking,, I’ve devise a way to siphon/
> >> wet vac out the fluid ... a u shaped steel line ,,
> >> There isn’t much room ,,
> >>
> >> Of course , if there has been a recent drop in reservoir level,, then a
> >> master cyl repair/ replacement is in order
> >>
> >> My take on it,,  Jamie
> >>
> >> > On Aug 16, 2020, at 9:51 AM, Erik Burtis <ewdb92 at gmail.com> wrote:
> >> >
> >> > I was thinking about this problem early this morning.  Let's see: You
> >> said
> >> > you replaced all the brake lines, so unless dirt got into the system
> at
> >> > that time or there is a defect, they shouldn't be the issue..  The
> >> problem
> >> > went away when you disconnected the brake booster.  I think this rules
> >> out
> >> > blockage in the lines or brake fluid issues.  This sounds like a
> >> buildup of
> >> > vacuum to me and when you stop driving and press the brakes, you
> release
> >> > the vacuum.  It can happen if the check valve is in backwards; can
> also
> >> > happen if the booster vent line is blocked (did it get pinched during
> >> your
> >> > spindle work?).  Do both front brakes drag?  If so, also an indication
> >> this
> >> > is not line related.  Maybe a failed booster would hold extra vacuum,
> >> but
> >> > it seems to me that they do the opposite.  One of the tests for a
> failed
> >> > booster is a change in rpms when you press the brake pedal.
> >> > Erik
> >> >
> >> >
> >> >>
> >> > _______________________________________________
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> >>
> >
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